MOST of the Vietnamese refugees working on the new Hong Kong airport are heroin addicts, it was claimed yesterday. The claim was made as construction worker Nguyen Van Thanh, 27, was jailed for six years for trafficking by the High Court. Prosecutor Yasmin Mahomed said Nguyen, who came to the territory in 1987, was arrested with 115.65 grams of heroin on July 5 last year at Pillar Point open camp. Defence counsel Wong Chi-kwong said Nguyen did not intend to sell the drugs for profit, but to share them with friends. He said: ''Most of the Vietnamese airport workers are drug users or drug addicts. The drug problem is a fairly big problem. Most of them are addicted to heroin.'' Mr Wong said Nguyen, who spent nearly all his wages on heroin, had been an addict since 1990, the year he was moved to Pillar Point after being given refugee status. Deputy Judge Wilson jailed Nguyen for six years for trafficking and one year for possession to run concurrent after the construction worker admitted both charges. Outside court, Inspector John Wong said the problem was not confined to the airport workers. ''Most of the Vietnamese at Pillar Point are drug addicts, both males and females. The dealing usually goes on at the camp, not the airport.'' Secretary for Works James Blake said no such claims had come to his attention in the past. ''It is not for me to comment on some claims that have been made in court of which I have no knowledge. ''As far as the Chek Lap Kok construction site, I can only say that all the contracts make it obligatory that the contractor ensures that any of his workers are not involved in any offence. ''I am unable to say whether there are any refugees employed on the site,'' he said.